Drama or plays are a genre of literature in which actors speak lines of dialogue rather than the story being told through narration. The earliest extant dramas, including the surviving Greek and Roman plays, were written in verse. Prose drama originated later, in the modern (post-Renaissance) period. Dramas written in verse are referred to as "dramatic poetry" or "verse drama". The main genres of verse drama are tragedy and comedy. Mixing of these genres, or the insertion of comic interludes in tragedy, was an Elizabethan innovation. Dramas intended to be read rather than performed are known as "closet dramas"; many 19th century verse dramas fall in this category.